Contenido principal

allpassbpc2bpc

Allpass filter for complex bandpass transformation

Description

[AllpassNum,AllpassDen] = allpassbpc2bpc(Wo,Wt) returns the numerator, AllpassNum, and the denominator, AllpassDen, of the first-order allpass mapping filter for performing a complex bandpass to complex bandpass frequency transformation. For more information, see Complex Bandpass to Complex Bandpass Frequency Transformation.

Examples

collapse all

This example shows how to design allpass mapping filter, changing the complex bandpass filter with the band edges at Wo1=0.2 and Wo2=0.4 to the new band edges of Wt1=0.3 and Wt2=0.6. Find the frequency response of the allpass mapping filter:

Wo = [0.2, 0.4]; Wt = [0.3, 0.6]; 
[AllpassNum, AllpassDen] = allpassbpc2bpc(Wo, Wt);
[ha, f] = freqz(AllpassNum, AllpassDen, 'whole');
plot(f/pi,-angle(ha)/pi, Wt, Wo, 'ro')
title('Mapping Function Wo(Wt)'); 
xlabel('New Frequency, Wt'); ylabel('Old Frequency, Wo');

Figure contains an axes object. The axes object with title Mapping Function Wo(Wt), xlabel New Frequency, Wt, ylabel Old Frequency, Wo contains 2 objects of type line. One or more of the lines displays its values using only markers

Input Arguments

collapse all

Frequency values to be transformed from the prototype filter, specified as a real vector with values in the range (-1,1).

Data Types: single | double

Desired frequency locations in the transformed target filter, specified as a real vector with values in the range (-1,1).

Data Types: single | double

Output Arguments

collapse all

Numerator of the mapping filter, returned as a complex-valued vector.

Data Types: double
Complex Number Support: Yes

Denominator of the mapping filter, returned as a complex-valued vector.

Data Types: double
Complex Number Support: Yes

More About

collapse all

Version History

Introduced in R2011a